Iron amido

Ligand deprotonation may result in some interesting ambiguities in oxidation state, which ultimately allow us to consider new patterns of reactivity. We begin by considering the iron(m) complex of a macrocyclic amine 5.18. Deprotonation of the amino group in the complex gives an iron(m)-amido complex 5.19 (Fig. 5-34). 

Figure 5-34. The deprotonation of an iron(m) complex of a macrocyclic amine to give an iron(m)-amido complex. The presence of the lone pair of electrons (negative charge) on the deprotonated nitrogen atom is emphasised ( ).

Figure 5-35. Tautomeric forms of the iron(in)-amido complex generated in Figure 5-34. The iron(n) complex 5.20 is simply a tautomeric form of 5.19, in which an electron has been transferred from nitrogen to the iron(m) centre.

However, the iron(m)-amido complex could also be written as an iron(n) amido radical complex 5.20. These two representations are, of course, simply limiting valence bond descriptions of the complex (Fig. 5-35). The difference simply involves the transfer of one electron from the lone pair on the nitrogen in 5.19 to the iron(ni) centre. 

Chatancin, via ring-closing metathesis, 11, 252 Chelate coordination, monoenes, in Pd(II) complexes, 8, 331 Chelated alkenes, with iron, 6, 133 Chelated allyl complexes, with iron, 6, 140 Chelating aryloxides, with Zr(IV), 4, 784 Chelating bis(amido) complexes, with Zr(IV), 4, 767 Chelating bis(amido) phosphine-donor complexes, with Zr(IV), 4, 816... 

A series of 4-alkylamido-2-hydroxybenzoic acids containing a different number of carbon atoms in the alkyl-amido group has been studied as model ligands for metal ion extraction in aqueous micellar solutions of nonionic surfactants. Their acid-base properties and reactivity towards metal ions in the presence of micelles were investigated. By operating at a proper temperature, the separation of the iron (III) chelate complexes into a micellar rich phase was achieved and the extraction efficiency was correlated with the ligand hydrophobicity. 

Ferrous anudo-sulphonate, Fe(S03.NH2)a.( )5H20, is obtained by dissolving iron wire in aqueous amido-sulphonic acid, and concentrating in vacuo.5 The crystals are bluish green in colour, deliquescent, and exceedingly soluble in water, from which they are not precipitated by alcohol, thereby differing from ferrous sulphate. The crystals appear to contain 5 molecules of combined water. 

Other cases in which second-order kinetics seemed to require an associative mechanism have subsequently been found to have a conjugate base mechanism (called S ICB, for substitution, nucleophilic, unimolecular, conjugate base in Ingold s notation ). These reactions depend on amine, ammine, or aqua ligands that can lose protons to form amido or hydroxo species that are then more likely to lose one of the other ligands. If the structure allows it, the ligand Irons to the amido or hydroxo group is frequently the one lost. 

E. TRIS[BIS(TRIMETHYLSILYL)AMIDO]IRON(III) (Tris(l,l, 1,3,3,3-hexa-methylsilazanato)iron(III))... 

The method is essentially the same as that described in synthesis A. The quantities of bis(trimethylsilyl)amine (0.10 mole) and butyllithium (0.093 mole) are again used, but the solvent is 100 mL of dry benzene (sodium-dried and distilled from calcium hydride). The addition of the anhydrous FeCls (9.8 g, 0.06 mole) leads to a slight warming of the reaction mixture. After 24 hours of stirring at room temperature, by which time the solution has assumed a dark-green coloration, the contents are briefly heated to reflux with an infrared lamp and the mixture is filtered. Concentration of the filtrate produces a mass of dark-green needle crystals, which are filtered, washed with a small amount of cold benzene, pumped dry, and sealed into ampules under vacuum. The yield of tris-[bis(trimethylsilyl)amido]iron(III) is about 10 g (62%). Satisfactory analyses have not been obtained due to this compound s high reactivity to air and moisture. 

Tris[bis(trimethylsilyl)amido]iron(III) crystallizes from benzene as dark-green, almost black, needles, very sensitive to air and moisture. The compound... 

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